{ diff(x1, t) = 0,
  diff(x2, t) = 0,
  diff(x3, t) = ((-1)*k12*(k1*x3*x18 - k4*x17) + (-1)*k12*(k1*x29*x3 - k4*x33))/k12,
  diff(x4, t) = (1*k12*k18*k64*x3 + (-1)*k12*k19*x4 + 1*k12*k9*k64*x17 + 1*k12*k9*k64*x33)/k12,
  diff(x5, t) = (1*k12*k20*k65*x4 + (-1)*k12*k21*x5 + (-1)*k12*(k31*x5*x10 - k32*x19) + (-1)*k12*(k44*x5*x25 - k45*x26) + (-1)*k12*(k50*x5*x28 - k51*x30))/k12,
  diff(x6, t) = 0,
  diff(x7, t) = ((-1)*k12*(k1*x7*x18 - k6*x15) + (-1)*k12*(k1*x29*x7 - k6*x34))/k12,
  diff(x8, t) = (1*k12*k22*k64*x7 + (-1)*k12*k23*x8 + 1*k12*k7*k64*x15 + 1*k12*k7*k64*x34)/k12,
  diff(x9, t) = (1*k12*k24*k65*x8 + (-1)*k12*k25*x9 + (-1)*k12*(k28*x10*x9 - k29*x18) + (-1)*k12*(k47*x9*x28 - k48*x29))/k12,
  diff(x10, t) = ((-1)*k12*(k28*x10*x9 - k29*x18) + 1*k12*k30*x18 + (-1)*k12*(k31*x5*x10 - k32*x19) + 1*k12*k33*x19 + (-1)*k12*x12*k34*x10/k35/(1 + x10/k35 + x25/k36 + x28/k37) + 1*k12*(k38*k68 - k39*x10) + 1*(k42*x36 - k43*x10))/k12,
  diff(x11, t) = ((-1)*k12*(k1*x11*x19 - k2*x16) + (-1)*k12*(k1*x11*x26 - k2*x27) + (-1)*k12*(k1*x11*x30 - k2*x32))/k12,
  diff(x12, t) = (1*k12*k16*k65*x13 + (-1)*k12*k17*x12)/k12,
  diff(x13, t) = (1*k12*k14*k64*x11 + (-1)*k12*k15*x13 + 1*k12*k3*k64*x16 + 1*k12*k3*k64*x27 + 1*k12*k3*k64*x32)/k12,
  diff(x14, t) = (1*k12*k26*k64*x21 + (-1)*k12*k27*x14 + 1*k12*k8*k64*x20 + 1*k12*k8*k64*x35)/k12,
  diff(x15, t) = 1*k12*(k1*x7*x18 - k6*x15)/k12,
  diff(x16, t) = 1*k12*(k1*x11*x19 - k2*x16)/k12,
  diff(x17, t) = 1*k12*(k1*x3*x18 - k4*x17)/k12,
  diff(x18, t) = (1*k12*(k28*x10*x9 - k29*x18) + (-1)*k12*k30*x18 + (-1)*k12*(k1*x3*x18 - k4*x17) + (-1)*k12*(k1*x7*x18 - k6*x15) + (-1)*k12*(k1*x21*x18 - k5*x20))/k12,
  diff(x19, t) = (1*k12*(k31*x5*x10 - k32*x19) + (-1)*k12*k33*x19 + (-1)*k12*(k1*x11*x19 - k2*x16))/k12,
  diff(x20, t) = 1*k12*(k1*x21*x18 - k5*x20)/k12,
  diff(x21, t) = ((-1)*k12*(k1*x21*x18 - k5*x20) + (-1)*k12*(k1*x29*x21 - k5*x35))/k12,
  diff(x22, t) = 0,
  diff(x23, t) = 0,
  diff(x24, t) = ((-1)*k12*k40*x24 + 1*k12*k41*k65*x14)/k12,
  diff(x25, t) = ((-1)*k12*(k44*x5*x25 - k45*x26) + 1*k12*k46*x26)/k12,
  diff(x26, t) = (1*k12*(k44*x5*x25 - k45*x26) + (-1)*k12*k46*x26 + (-1)*k12*(k1*x11*x26 - k2*x27))/k12,
  diff(x27, t) = 1*k12*(k1*x11*x26 - k2*x27)/k12,
  diff(x28, t) = ((-1)*k12*(k47*x9*x28 - k48*x29) + 1*k12*k49*x29 + (-1)*k12*(k50*x5*x28 - k51*x30) + 1*k12*k52*x30 + (-1)*k12*x12*k53*x28/k54/(1 + x28/k54 + x25/k55 + x10/k56) + 1*(k57*k70 - k58*x28))/k12,
  diff(x29, t) = (1*k12*(k47*x9*x28 - k48*x29) + (-1)*k12*k49*x29 + (-1)*k12*(k1*x29*x3 - k4*x33) + (-1)*k12*(k1*x29*x7 - k6*x34) + (-1)*k12*(k1*x29*x21 - k5*x35))/k12,
  diff(x30, t) = (1*k12*(k50*x5*x28 - k51*x30) + (-1)*k12*k52*x30 + (-1)*k12*(k1*x11*x30 - k2*x32))/k12,
  diff(x31, t) = 0,
  diff(x32, t) = 1*k12*(k1*x11*x30 - k2*x32)/k12,
  diff(x33, t) = 1*k12*(k1*x29*x3 - k4*x33)/k12,
  diff(x34, t) = 1*k12*(k1*x29*x7 - k6*x34)/k12,
  diff(x35, t) = 1*k12*(k1*x29*x21 - k5*x35)/k12,
  diff(x36, t) = ((-1)*(k42*x36 - k43*x10) + (-1)*k13*(k59*x36*x38 - k60*x39) + (-1)*k13*(k61*x40*x36 - k62*x41) + 1*k13*k63*k71)/k13,
  diff(x37, t) = 0,
  diff(x38, t) = (-1)*k13*(k59*x36*x38 - k60*x39)/k13,
  diff(x39, t) = 1*k13*(k59*x36*x38 - k60*x39)/k13,
  diff(x40, t) = (-1)*k13*(k61*x40*x36 - k62*x41)/k13,
  diff(x41, t) = 1*k13*(k61*x40*x36 - k62*x41)/k13,
  diff(x42, t) = 0 }